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In physics, specifically electromagnetism, the magnetic flux through a surface is the surface integral of the normal component of the magnetic field B over that surface. It is usually denoted Φ or Φ B. The SI unit of magnetic flux is the weber (Wb; in derived units, volt–seconds or V⋅s), and the CGS unit is the maxwell. [1]
In physics, the magnetomotive force (abbreviated mmf or MMF, symbol ) is a quantity appearing in the equation for the magnetic flux in a magnetic circuit, Hopkinson's law. [1] It is the property of certain substances or phenomena that give rise to magnetic fields : F = Φ R , {\displaystyle {\mathcal {F}}=\Phi {\mathcal {R}},} where Φ is the ...
Magnetic pole model for H and Ampèrian loop model for B yield the identical field outside of a magnet. Inside they are very different. The field of a magnet is the sum of fields from all magnetized volume elements, which consist of small magnetic dipoles on an atomic level.
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal n̂, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
The above equations are the microscopic version of Maxwell's equations, expressing the electric and the magnetic fields in terms of the (possibly atomic-level) charges and currents present. This is sometimes called the "general" form, but the macroscopic version below is equally general, the difference being one of bookkeeping.
In physics, the weber (/ ˈ v eɪ b-, ˈ w ɛ b. ər / VAY-, WEH-bər; [1] [2] symbol: Wb) is the unit of magnetic flux in the International System of Units (SI). The unit is derived (through Faraday's law of induction) from the relationship 1 Wb = 1 V⋅s (volt-second). A magnetic flux density of 1 Wb/m 2 (one weber per square metre) is one tesla.
The magnetic flux density (magnetic field) having the unit Wb/m 2 is denoted by B, and magnetic flux is defined analogously: [13] [14] = with the same notation above. The quantity arises in Faraday's law of induction , where the magnetic flux is time-dependent either because the boundary is time-dependent or magnetic field is time-dependent.
In electromagnetics, the term magnetic field is used for two distinct but closely related vector fields denoted by the symbols B and H. In the International System of Units, the unit of B, magnetic flux density, is the tesla (in SI base units: kilogram per second squared per ampere), [5]: 21 which is equivalent to newton per meter